#include <stdio.h>
#include <limits.h>
#include <ctype.h>

void to_bin(int);

int main(void)
{
    unsigned long n;
    printf("Please enter a integer:");

    while (scanf("%ld",&n) == 1) {
        to_bin(n);

        printf("\nPlease enter a integer:");
    }

    return 0;
}

void to_bin(int n) {
    if (n >= 2)
        to_bin(n / 2);

    printf("%d", n % 2);

    return;
}
